DE60100038T3 - Olefin-based thermoplastic elastomer and molded article - Google Patents

Description

background the invention

The The present invention relates to an olefin-based thermoplastic Elastomer comprising a composition containing a Propylene-based resin and an olefin-based copolymer rubber, and more particularly to an olefin-based thermoplastic Elastomer, which is outstanding in the castability, transferability of embossed patterns and mechanical strength, is able to produce a poured product that is free of defects of appearance, such as uneven luster, Welds and Flowlines, even if its strength varies in a wide range, and is suitable for forming Automotive interior trim or parts, in particular for a cover for stowing an airbag.

In In recent years, thermoplastic elastomers such as styrene have been used based elastomers, olefin based elastomers, polyesters based elastomers, polyamide-based elastomers Polyurethane-based elastomers, from the point of view of productivity and recyclability Attention found, which are rubbery soft materials and have a good pourability, those with the thermoplastic resins without vulcanization is compatible, and are commonly used in numerous applications such as automotive parts, electrical devices, medical apparatus or its components, electric cables and other. Among these elastomers are compositions, those based on propylene resins and an olefin-based copolymer rubber such as an ethylene-propylene copolymer rubber or an ethylene-propylene-non-conjugated diene copolymer rubber, or Olefin-based thermoplastic elastomers obtained by kinematic heat treatment the above compositions in the presence of an organic Peroxides were obtained to allow the olefin-based Copolymer can be crosslinked and a partially crosslinked product forms due to their low cost as particularly noteworthy economically useful Materials, noticed. In addition, the elastomers have adequate flexibility and prevent embossed patterns from being removed, even if subjected to a thermal molding process Be positive studies have been carried out to these elastomers in interior trim of automobiles or parts thereof as an alternative Materials for to apply conventional soft vinyl chloride resins.

cast Products such as typical automotive interior trim or parts of it generally ribs to ensure their mechanical strength, or other components or fittings for attachment to a Basic structure and therefore they have both thin-walled and thick-walled parts, what a big change the strength leads. Such a change the strength tends to cause defects in appearance, such as a non-uniform shine, welds and flowlines on the surface of the poured product. As the olefin-based thermoplastic Elastomers especially not only in the form of a mixture, but even if they are partially cross-linked, they tend to have a not even distribution or a coarse grained To cause distribution of networked gums. Because of this, suffer from olefin-based thermoplastic elastomers rather under the above-mentioned defects in appearance.

In order to solve the problems of the above-mentioned defects in appearance, Japanese Patent Application Laid-Open (KOKAI) No. 8-176394 (1996) describes a thermoplastic elastomer composition having a strand expansion ratio of not less than 1.8 and a shear rate of 6.8 x 10 ³ sec ^-1 and a propylene-based block copolymer resin, a specific hydrogenated aromatic vinyl-conjugated diene block copolymer, and an ethylene-α-olefin copolymer rubber and paraffin-based process oils. Japanese Patent Application Laid-Open (KOKAI) No. 10-259281 (1998) also describes a thermoplastic elastomer composition comprising a propylene-based resin, a specific hydrogenated vinyl aromatic-conjugated diene block copolymer, and an ethylene-α-olefin copolymer rubber.

However, as a result of the detailed research by the present inventors, it has been found that these conventional thermoplastic elastomer compositions fail to fully satisfy the requirements resulting from a reduction in the strength of the molded products due to the prevailing tendency for lighter automobile parts or increase in size molded products due to the prevalent tendency for a reduced number of parts, in particular the claim that the cast products have large changes in thickness, for example a cover for an airbag, with a thin-walled part having a thickness no greater than 1 mm is that free from Defects in appearance, such as inconsistent gloss, welds and flow lines, should inflate or unfold an airbag contained therein.

Under these circumstances, it has been found that the described olefin-based thermoplastic elastomer obtained by blending a propylene-based resin and an olefin-based copolymer gum has a specific ratio (N ₁ / SS) of the first normal stress difference (N ₁ ). has excellent pourability, transferability of embossed patterns and mechanical strength to shear stress (SS). Based on these findings, the present invention has been achieved.

Summary the invention

One The object of the present invention is to provide an olefin-based thermoplastic elastomer provided which is a composition which comprises a propylene-based resin and an olefin containing copolymer gum contains not only an excellent pourability, transferability of the embossed patterns and mechanical strength but also capable of producing a molded product to disposal to provide that is free of defects in appearance, such as uneven gloss, Welds and Flowlines.

Around To achieve this object, according to a first aspect of the invention an olefin-based thermoplastic elastomer is provided as defined in claim 1.

In a second aspect of the invention, there is provided a molded product molded from said olefin-based thermoplastic elastomer defined in the above-mentioned first aspect, having an opening and / or a planar base plate comprising:
a thin-walled part having a thickness in the range of 5 to 50% of the thickness of said flat base plate,
a thick-walled part having a thickness in the range of 110 to 200% of the thickness of said planar base plate, and / or
a rib having a thickness in the range of 5 to 200 of the thickness of the planar base plate.

Short description the drawings

1 (a) Fig. 10 is a cross section showing a thin-walled part of a molded product made of an olefin-based thermoplastic elastomer according to the invention;

1 (b) is a cross-section showing a thick-walled part of the molded product that is in 1 (a) is shown; and

1 (c) is a cross-section showing a rib of the molded product which is in 1 (a) is shown.

2 (a) Fig. 10 is a plan view illustrating a test piece for uneven luster and welds made of an olefin-based thermoplastic elastomer according to the invention; and

2 B) is a cross section along the AA line of the 2 (a) have been done.

3 (a) Fig. 10 is a plan view showing another test piece for uneven gloss and welds made of an olefin-based thermoplastic elastomer according to the invention; and

3 (b) is a cross section along the line BB of 3 (a) ,

detailed Description of the invention

In the present invention, examples of the propylene-based resins as the component (A) contained in the olefin-based thermoplastic elastomer may include propylene homopolymer, or copolymers of propylene with other α-olefins having 2 to 10 carbon atoms, such as ethylene, 1 Butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 4-methyl-1-hexene, 1-Hep ten, 1-octene and 1-decene. Specific examples of the propylene-based resins may include propylene-ethylene copolymers, propylene-1-butene copolymers, propylene-ethylene-1-butene copolymers, propylene-4-methyl-1-pentene copolymers. Of these propylene-based resins, propylene homopolymer and propylene-ethylene copolymers are preferable. The ethylene content of the propylene-ethylene copolymers is preferably not more than 15% by weight, and more preferably not more than 10% by weight. The lower limit is preferably 1% by weight.

The Propylene-based resin used in the present invention may be characterized by the polymerization processes are made using either Ziegler catalysts or use metallocene catalysts. Of these procedures will be those which use metallocene catalysts are preferred.

meanwhile are polymerization processes for the production of propylene based resins using metallocene catalysts already known in the art. For example, propylene based resins by polymerizing propylene in the presence a metallocene catalyst which comprises: (a) a cyclopentadienyl group containing component of a transition metal such as Titanium, zirconium and hafnium, (b) an aluminum oxy-constituent, a Lewis acid, an ionic component that is capable of interacting with the component (a) reacting to convert component (a) into a cation, or clays, clay minerals and ion-exchanging layer components, and if necessary (c) an organoaluminum component through which Vapor phase polymerization process, the bulk polymerization process, the solution polymerization method.

The propylene-based resin used in the invention has a ratio (Mw / Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of 2.5: 1 to 4.0: 1, preferably 2.5: 1 to 3.5: 1 when measured by gel permeation chromatography. When the ratio (Mw / Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) is less than 2.5: 1, the olefin-based thermoplastic elastomer may have a small first normal stress difference (N ₁ ) caused by the Staged shear test, which will be described in detail below, is determined. As a result, the ratio (N ₁ / SS) of the first normal voltage difference (N ₁ ) to the shearing stress (SS) is too small, so that flow lines can be caused. On the other hand, when the ratio (Mw / Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) is more than 4.0: 1, the obtained olefin-based thermoplastic elastomer may have a large first normal stress difference (N ₁ ). It follows that the ratio (N ₁ / SS) of the first normal stress difference (N ₁ ) to the shear stress (SS) is too large, so that uneven gloss or welds may be caused.

The used according to the invention Propylene based resin preferably has a melt flow from 10 to 120 g / 10 min, more preferably 15 to 100 g / 10 min, when it at 230 ° C under a load of 21.18N according to JIS K7210. When the melt flow rate of the propylene-based resin is less is 10 g / 10 min, the obtained olefin-based thermoplastic can Elastomer in terms of pourability be disadvantageous. On the other hand, if the melt flow of on Propylene-based resin is more than 120 g / 10 min make it difficult to obtain the resulting olefin-based thermoplastic Elastomer to give sufficient mechanical strength.

In of the present invention are examples of the olefin-based Copolymer gums as component (B), which are based on olefin thermoplastic elastomer are included, copolymers by the ordinary Copolymerizing two or more α-olefins having 2 to 10 carbon atoms such as ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 4-methyl-1-hexene, 1-heptene, 1-octene, 1-decene; or copolymers which were obtained by the above-mentioned copolymers with non-conjugated Have been copolymerized such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 6-methyl-1,5-heptadiene, 1,4-octadiene, 7-methyl-1,6-octadiene, cyclohexadiene, cyclooctadiene, dicyclopentadiene, 5-methylene-norbornene-2, 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, 5-isopropenyl-2-norbornene. Specific examples of the olefin-based copolymer gums can lock in: Ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-1-hexene copolymers, Ethylene-outene copolymers, propylene-1-butene copolymers, ethylene-propylene-1,4-hexadiene copolymers, Ethylene glycol-dicyclopentadiene copolymers, ethylene-propylene-5-ethylidene-2-norbornene copolymers.

Of these olefin-based copolymer gums, preferred are ethylene copolymers with the other α-olefin or ethylene copolymers with the other α-olefin and non-conjugated diene. The content of the α-olefin in the above-mentioned copolymers is preferably 10 to 60% by weight, more preferably at 15 to 55% by weight. When the content of the other α-olefin is less than 10% by weight, the olefin-based thermoplastic elastomer tends to decrease in mechanical strength, such as low-temperature impact resistance. On the other hand, when the content of the other α-olefin is more than 60% by weight, the obtained olefin-based thermoplastic elastomer is deficient in mechanical strength such as heat resistance stiffness. The content of the non-conjugated diene contained in the above-mentioned olefin-based copolymer which is further copolymerized with a non-conjugated diene, however, at preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight. %.

The olefin-based copolymer gum used in the present invention can also be used by any copolymerization method of either Ziegler catalysts, such as vanadium components or metallocene catalysts.

The olefin-based copolymer gum used in the present invention has a melt flow of preferably 0.1 to 20 g / 10 min, more preferably 0.2 to 15 g / 10 min when at 230 ° C at a load of 21.18 N according to JIS K7210 is measured. When the melt flow rate of the olefin-based copolymer gum is less than 0.1 g / 10 min, the resulting olefin-based tends thermoplastic elastomer, in terms of pourability to decrease. On the other hand, it can be difficult to on olefin-based thermoplastic elastomer sufficient mechanical strength when the melt flow of the olefin-based melt Copolymer gum is more than 20 g / 10 min.

The according to the invention Olefin-based thermoplastic elastomer contains 35 to 60% by weight of ingredient (A) and 65 to 40% by weight of the ingredient (B). When the content of the component (A) is less than 30% by weight and the Content of the ingredient (B) is more than 70% by weight, the resulting olefin-based thermoplastic elastomer with respect to the mechanical strength, such as heat resistance stiffness, decrease. If the content of the component (A) is, on the other hand, more than 70% by weight and the Content of the component (B) is less than 30% by weight, tends obtained, olefin-based thermoplastic elastomer thereto, in terms of mechanical strength, such as the low temperature impact strength decrease.

The olefin-based thermoplastic elastomer may further further contain a styrene-based thermoplastic elastomer as component (C) to increase its mechanical strength such as low-temperature impact resistance and tear strength, as well as the resistance to scratches and wear of the surface of the molded products that are obtained from this. The content of the component (C) is 1 to 20 parts by weight, preferably 3 to 18 parts by weight, based on 100 parts by weight of the sum of the components (A) and (B). When the content of the styrene-based thermoplastic elastomer (C) is more than 20 parts by weight, the obtained olefin-based thermoplastic elastomer may tend to fail, the ratio (N ₁ / SS) of the first normal stress difference (N ₁ ) to the shear stress (SS) of about 0.6: 1 to 1.4: 1 as defined by the present invention. Such a case, the ratio (N ₁ / SS) of the olefin-based thermoplastic elastomer can be controlled by adding a gum softening agent as described below.

The styrene-based thermoplastic elastomer, as an ingredient (C) may be in the form of a block copolymer having a linear, branched or radially expanded molecular structure, or a combination from containing aromatic vinyl polymer blocks as solid segments, and conjugated diene polymer blocks or random conjugated aromatic diene copolymer blocks as soft segments. Examples of these styrene-based thermoplastic Elastomers can are represented by aromatic vinyl-conjugated diene block copolymers, those made of aromatic vinyl polymer as blocks serving as hard segments and conjugated random aromatic diene vinyl copolymer blocks are composed as soft segments and from hydrogenated aromatic vinyl-conjugated diene block copolymers, in which the double bonds of the latter conjugated diene can be hydrogenated.

The Examples of the aromatic vinyls used in these block copolymers are included Styrene, α-methylstyrene, p-methylstyrene, dimethylstyrene. Of these aromatic Vinyls, styrene is preferred. Examples of the conjugated dienes may be butadiene, Isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene. From These conjugated dienes are butadiene, isoprene and a mixture preferred on butadiene and isoprene.

The The abovementioned block copolymer as constituent (C) contains the aromatic Vinyl polymer blocks in an amount of preferably 5 to 50% by weight, more preferably 10 to 40% by weight. additionally the conjugated diene polymer blocks are in the form of a hydrogenated In which preferably not less than 80%, more preferably not less than 95% of the double bonds are hydrogenated.

The The above-mentioned block copolymer as component (C) has a melt flow rate of preferably 0.05 to 20 g / 10 min, more preferably 0.1 to 15 g / 10 min when at 230 ° C under a load of 21.18N according to JIS K7210.

The olefin-based thermoplastic elastomer of the present invention Invention can also a softening agent for contain hydrocarbon-based gums as constituent (D), usually moldability, flexibility etc. to mediate. The content of the component (D) is preferably 1 to 20 parts by weight, more preferably 3 to 18 parts by weight based on 100 parts by weight of the sum of the components (A) and (B). When the composition of the present invention also has a Component (C) additionally to component (D) contains, the content of the component (D) is preferably not more than 150 Parts by weight based on 100 parts by weight of component (C) from the standpoint of the anti-bleed property of the composition.

The Softening agent for hydrocarbon-based gums as component (D) generally in the form of a mixture of an aromatic ring compound, a naphthene ring compound or a paraffin chain compound in front. The softening agents for hydrocarbon-based high-boiling petroleum fractions, which are divided into paraffin-based oils, the Paraffin chain carbon atoms in an amount of not less as 50% based on the total number of carbon atoms; on Naphthenic based oils, the naphthene ring carbon atoms are in an amount of 30 to 45% to the total number of carbon atoms; and aromatic oils that an aromatic ring with carbon atoms in an amount of not less than 30% based on the total number of carbon atoms contain. Of these softening agents, paraffin-based oils are preferred.

The Softening agent for hydrocarbon-based gums as component (D) a weight average molecular weight of preferably 300 to 2,000, more preferably 500 to 1,500; at 40 ° C, a kinematic viscosity of preferred 20 to 800 cSt, more preferably 50 to 600 cSt; a liquid point of preferred -40 up to 0 ° C, even more preferred -30 up to 0 ° C; and a flashpoint of preferably 200 to 400 ° C, more preferably 250 to 350 ° C. The olefin-based thermoplastic elastomer of the present invention Invention contains the propylene-based resin (A) and the olefin-based resin Copolymer gum (B) as essential ingredients, and may further if necessary obtained, the styrene-based thermoplastic elastomer as Component (C) and the softening agent for hydrocarbon-based gums as component (D). Furthermore For example, the olefin-based thermoplastic elastomer can be kinetic in Presence of an organic peroxide are heat treated, if necessary.

Here, the "kinetic heat treatment" means kneading of the above-mentioned composition while keeping it in a molten state using a kneading machine. The kinetic heat treatment allows ultrahigh molecular weight polymers contained in the propylene-based resin component (A) to decompose under the action of the organic peroxide, thereby not only increasing the fluid of the olefin-based thermoplastic elastomer but also the first normal stress difference (FIG. N ₁ ) and the shearing stress (SS) in the step shear test, which will be described in detail below.

The organic peroxides used in the kinetic heat treatment may be those normally used to prepare conventional, partially crosslinked, olefin-based thermoplastic elastomers. Specific examples of the organic peroxides may include: dialkyl peroxides such as di-t-butyl peroxides, t-butyl cumyl peroxides, dicumyl peroxides, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5 -di (t-butylperoxy) hexyn-3, 1,3- or 1,4-bis (t-butylperoxyisopropyl) benzene and 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane; Peroxyesters such as t-butyl peroxybenzoate, t-butyl peroxyisopropyl carbonate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane and 2,5-dimethyl-2,5-di (benzoylperoxy) hexyn-3; Diacyl peroxides such as lauroyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide and 2,4-dichlorobenzoyl peroxide; Hydroperoxides such as cumene hydroperoxide and diisopropylbenzene hydroperoxide. Among these organic peroxides, preferred are dialkyl peroxides and peroxyesters, and dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyn-3 , 1,3- or 1,4-bis (t-butylperoxyisopropyl) benzene, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (benzoylperoxy ) hexane and 2,5-dimethyl-2,5-di (benzoylperoxy) hexyn-3 are still to come ferred.

The organic peroxide can be used in any amount, as long as it is the ultrahigh molecular weight polymers present in the component (A) are efficient. The amount of organic used Peroxide is preferably in the range of 0.005 to 0.3 parts by weight, more preferably 0.01 to 0.25 parts by weight based on 100 parts by weight the sum of the propylene-based resin as component (A) and the olefin-based copolymer gum as component (B).

The olefin-based thermoplastic elastomer of the present invention Invention can be achieved by properly selecting the propylene-based Resin as component (A) and the olefin-based copolymer gum as component (B) and the appropriate control of the amount of organic peroxide or the kneading time. Yet more specifically, the olefin-based thermoplastic elastomer of the present invention, by reacting with propylene based resin as constituent (A) with a ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight selected from 2.5: 1 to 4.0: 1 becomes. In this case, a small amount of the propylene-based resin is as component (A), its ratio (Mw / Mn) outside of the range of 2.5: 1 to 4.0: 1 is added to the composition, as long as the composition obtained still has the properties that are within the scope of the present invention.

The olefin-based thermoplastic elastomer of the present invention Invention may also continue other resins or gums contain, as long as the intended effects of the present invention are not affected by added this become. Furthermore For example, the olefin-based thermoplastic elastomer of the present Invention as necessary contain various additives that are normally used to manufacture thermoplastic elastomers are used, such as Antioxidants, heat stabilizers, light stabilizers, ultraviolet light absorbing agents, antistatic agents, Anti-blocking agents, lubricants, anti-fogging agents, dispersants, Neutralizing agents, nucleating agents, conductivity improving agents Agents, antibacterial agents, flame retardants, dyes, fillers, as long as the intended effects of the present invention are not to the contrary be influenced by their addition.

The olefin-based thermoplastic elastomer of the present invention Invention can be prepared by using the propylene-based Resin as component (A) and the olefin-based copolymer gum as component (B) together with, if necessary, the styrene-based one thermoplastic elastomer as component (C), the plasticizer agent for on Hydrocarbon based gums as ingredient (D) and others Additives, all for usually in the form of powder or granules evenly with the aid of a Henschel mixer, a super mixer, a V-type mixer, one Tumbler Mixer, a Ribbon Mixer or similar and the melt-kneading of the resulting mixture a temperature of about 180 to about 280 ° C with Help of a Henschel mixer, Super Mixer, V-Type Mixer, Tumbler Mixer, Ribbon Mixer. By mixing and melt kneading, the mixture can be kinetic in the simultaneous presence of the above-mentioned organic peroxide heated become. As the components (B) and (D) may also be an oil-extended Gum, by temporarily adding the Component (D) during the preparation of the component (B) is produced.

The olefin-based thermoplastic elastomer of the invention must have a ratio (N ₁ / SS) of the first normal stress difference (N ₁ ) to the shear stress (SS) of 0.6: 1 to 1.4: 1, preferably 0.7: 1 to 1, 3: 1, when the step shear test at a temperature of 200 ° C and a shear rate of 25.1 sec ^{-1 is} performed.

If the ratio (N ₁ / SS) of the first normal stress difference (N ₁ ) to the shear stress (SS) is less than 0.6: 1, the melt front load on molding is too large, so that the products obtained under the jetting phenomenon or under Flow lines suffer. On the other hand, when the ratio (N ₁ / SS) of the first normal stress difference (N ₁ ) to the shear stress (SS) is more than 1.4: 1, the melt front load on molding is too low, so that the obtained molded products of one not only uneven gloss, but also suffer from welds due to the drop in fusion pressure at the welded parts. That is, when the ratio (N ₁ / SS) is out of the range specified in the present invention, appearance defects occur in the molded products.

The shear stress (SS) of the olefin-based thermoplastic elastomer of the present invention is preferably not more than 15,000 Pa. If the shear stress (SS) exceeds 15,000 Pa is, the flowability of the elastomer in molding is lowered, so that the molded product obtained tends to have not only flow lines but also other defects in appearance such as ski resort shots and lines or sink marks. The lower limit is preferably 6,000 Pa.

The shear stress (SS) and the first normal stress difference (N ₁ ) are obtained as fixed values thereof when measured by the following methods. This means that a cone plate with a diameter of 25 mm and an opening angle with a radian measure of 0.1 a shear stress test at a temperature of 200 ° C and a shear rate of 25.1 sec ^-1 using a kinematic viscoelastometer "MECHANICAL SPECTROMETER RMS-800 "manufactured by Rheometrics Corp. produced is subjected.

The olefin-based thermoplastic elastomer of the present invention has a melt flow rate of preferably 1 to 60 g / 10 minutes when measured at 230 ° C under a load of 21.18 N according to JIS K7210; a modulus of elasticity of preferably not more than 200 MPa when measured in accordance with JIS K 7171; and a notch impact strength of preferably not less than 30 kJ / m ² when measured at -40 ° C in accordance with JIS K7110. The lower limit of the elasticity mode is more preferably 50 Mpa.

The olefin-based thermoplastic elastomer of the present invention can be molded into the desired molded products by the extrusion molding method, the injection molding method, the injection-stamping method, the injection foaming method, the point-hollow molding method, the compression molding method or the like. In particular, the olefin-based thermoplastic elastomer of the present invention is suitable for producing a molded product such as an automobile interior or stamped-pattern parts or the like having a large change in thickness and, as in FIG 1 (A) to 1 (C) shown a flat base plate 1 with a thickness (t ₀ ), a thin-walled part 2 with a thickness (t ₁ ) in the range of 5 to 50% of the thickness (t ₀ ) of the plane base plate (t ₁ = t ₀ × (0.05 ~ 0.5)) (see 1 (a) ), a thick-walled part 3 with a thickness (t ₂ ) in the range of 110 to 200 of the thickness (t ₀ ) of the planar base plate (t ₂ = t ₀ x (0.1 ~ 2.0)) (see 1 (b) ), a rib 4 with a thickness (t ₃ ) in the range of 5 to 200 of the thickness (t ₀ ) of the plane base plate (t ₃ = t ₀ × (0.05 ~ 2.0)) (see 1 (c) ) and / or an opening, for example for producing an injection-molded lid for containing an airbag. Such an airbag cover may be formed individually or in a composite form that is inserted in the instrument panel, the door panel interior or the paneling.

Regarding the Conditions for the injection molding of the invention, on Olefin-based thermoplastic elastomer, the casting temperature is in the area for usually approximately 100 to about 300 ° C, preferred approximately 150 to about 280 ° C; of the Injection pressure is in the range of for usually about 5 to approximately 100 MPa, preferably about 10 to about 80 MPa; and the casting temperature is in the range of usually about 20 to approximately 80 ° C, preferred approximately 20 to about 60 ° C.

According to the present The invention will comprise an olefin-based thermoplastic elastomer composition a propylene-based resin and an olefin-based resin Copolymer gum available not only outstanding pourability, transferability the embossed pattern and mechanical strength owns but is also able to produce a cast product that is free of defects in appearance, such as the uneven shine, welds and Flowlines, even with big ones changes the strength.

Examples

The The present invention will be explained below in more detail with reference to FIGS following examples are shown. These examples are only to illustrate and not the present invention restrict.

The propylene-based resin (A), the olefin-based copolymer gum (B), the styrene-based thermoplastic elastomer (C), the Softening agent for hydrocarbon-based silencers (D) and the following Examples of organic peroxide used in Examples and Comparative Examples are shown below.

(A) Propylene based Resin:

• A-1: Propylene homopolymer obtained by the polymerization using a Ziegler catalyst was prepared with a Mw / Mn ratio of 3.3 and a melt flow rate of 50 g / 10 min;
• A-2: Propylene-ethylene block copolymer prepared by polymerization using a Ziegler catalyst and having an ethylene content of 4.0% by weight, a Mw / Mn ratio of 4.0 and a melt flow rate of 100 g / 10 min;
• A-3: propylene-ethylene random copolymer prepared by the polymerization using a metallocene catalyst and with an ethylene content of 2.3% by weight, a Mw / Mn ratio of 3.0 and a melt flow of 60 g / 10 min;
• A-4: Propylene-ethylene block copolymer prepared by the polymerization using a Ziegler catalyst 4.0 and having an ethylene content of wt.%, Mw / Mn ratio of 7.0 and a melt flow of 60 g / 10 min; and
• A-5: propylene ethylene random copolymer prepared by the polymerization using a Ziegler catalyst, and with an ethylene content of 3.5% by weight, a Mw / Mn ratio of 4.8 and a melt flow of 50 g / 10 min.

(B) Olefin-based copolymer gum:

• B-1: ethylene-1-octene copolymer gum with a 1-Octene content of 24 wt.% And a melt flow rate of 2.3 g / 10 min;
• B-2: Ethylenepropylene copolymer gum having a propylene content of 26% by weight and a melt flow rate of 3.0 g / 10 min;
• B-3: ethylene-propylene-5-ethylidene-2-norbornene copolymer gum with a propylene content of 25 wt.%, a 5-ethylidene-2-norbornengehalt of 15% by weight and a melt flow rate of 1.5 g / 10 min; and
• B-4: ethylene-1-hexene copolymer gum having a 1-hexene content of 23% by weight and a melt flow rate of 1.0 g / 10 min.

(C) Styrene-based thermoplastic elastomer:

• C-1: hydrogenated product of a block copolymer, composed of styrene homopolymer blocks and butadiene homopolymer blocks with a styrene content of 29% by weight, a percentage of hydrogenation of 99% and a melt flow of 0.1 to 0.5 g / 10 min; and
• C-2: Hydrogenated product of a block copolymer consisting of styrene homopolymer blocks and random butadiene / styrene copolymer blocks, with a styrene content of 10% by weight, a percentage of hydrogenation of 99% and a melt flow of 8 to 10 g / 10 min. Of the Melt flow rate of the above components (A), (B) and (C) were at a temperature of 230 ° C under a load of 21.18 N according to JIS K7210 measured.

(D) softening agent for on Hydrocarbon-based gums:

• D-1: Paraffin-based oils with one weight average molecular weight of 746, a kinematic viscosity at 40 ° C of 382 cSt, a fluid point of -15 ° C 'and a flash point of 300 ° C.

Organic peroxide:

2,5-dimethyl-2,5-di (t-butylperoxy) hexane

Examples 1 to 19 and Comparative Examples 1 to 3:

0.1 Part by weight of tetrakis [methylene-3- (3'-5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane as an antioxidant was added to 100 parts by weight of the sum of the constituents (A), (B), (C) and (D) and the organic peroxide as shown in Table 1, added. The obtained mixture was melt-kneaded and used at 200 ° C a twin-screw extruder with a cylinder diameter of 45 mm and a ratio L / D of 33 ("PCM45" manufactured by Ikegai Tekko Co., Ltd.), whereby the olefin-based thermoplastic elastomer was obtained.

Of the Melt flow of the resulting olefin-based thermoplastic Elastomers were measured by the following methods. The results are shown in Table 1.

Melt flow rate:

Of the Melt flow became 230 ° C under a load of 21.18 N according to JIS K 7210 measured.

In addition, the respective olefin-based thermoplastic elastomers prepared above were subjected to a shear stress test by the following methods for determining the shearing stress (SS) and the first normal stress difference (N ₁ ) and the ratio (N ₁ / SS) of the first Normal voltage difference (N ₁ ) to the shear stress (SS) was calculated from this. The results are shown in Table 1.

Shear stress (SS) and first normal stress difference (N ₁ ):

Using a kinematic viscoelastometer "MECHANICAL SPECTROMETER RMS-800" manufactured by Rheometrics Corp., a cone plate having a diameter of 25 mm and an opening angle of a radian measure of 0.1 was subjected to a shear stress test at a temperature of 200 ° C Subjected to shear rate of 25.1 sec ^-1 . The shear stress (SS) and the first normal stress difference (N ₁ ) were respectively determined therefrom as stationary values obtained after the above-mentioned measurement.

Then were the corresponding obtained olefin-based thermoplastic Elastomer injection molded by an injection molding machine of inline thread type IS170 ", manufactured from Toshiba Kikai Co., Ltd.) at a spray temperature of 220 ° C, one Injection pressure of 50 MPa and a casting temperature of 40 ° C, making a test piece was made with the following shape. The test piece thus obtained was observed and measured by the following methods to determine whether an uneven shine, Welds and flowlines have been caused or not, and the luster of the embossed pattern to investigate. The results are shown in Table 1.

Uneven shine and welds:

• (1) As in 2 (a) and 2 B) A 120 mm square flat plate of 4 mm thickness 5 was provided with a linear thin-walled part 6 in the center of one of the surfaces, including a base having a thickness of 0.6 mm, a width of 1 mm and a length of 30 mm and opposing sloping surfaces which form an outwardly open depression with an angle of 60 ° when viewed in cross-section. Further, similar 30 mm-long thin-walled parts projecting perpendicularly through the opposite ends of the above-mentioned central thin-walled parts and each having opposite ends having slightly curved parts were cast on the same surface of the flat plate, thereby producing the test piece (1) has been.
• (2) As in 3 (a) and 3 (b) shown was a 190 mm square flat plate with 4 mm thickness 10 with a center on its surface with a square frame-like rib 11 made with a thickness of 4 mm, a height of 20 mm and an inner surface of 91 mm ² . Furthermore, it became a linear thin-walled part 12 formed with a thickness of 0.6 mm and a width of about 2 mm on the same surface of the flat plate to project centrally over the square frame-like rib. In addition, one half of the same surface of the flat plate separated from the other half by a central line extending perpendicular to the linear thin-walled part, Grain C 13 was poured each with a depth of 100 μm, while the other surface half 14 remained in a mirror-smooth state, whereby the test piece (2) was prepared.

• A: Keinen oder fast keinen ungleichmäßigen Glanz und Schweißnähte wurden beobachtet.
• B: Leicht ungleichmäßiger Glanz wurde erkannt, aber fast keine Schweißnähte wurden beobachtet.
• C: Geringfügiger ungleichmäßiger Glanz und Schweißnähte wurden beobachtet.
• D: Schwerer ungleichmäßiger Glanz und Schweißnähte wurden erkannt.

The appearances of the respective test pieces (1) and (2) were observed with the naked eye, and the uneven gloss and welds were examined, with the steps A to 4 being practically acceptable.

• A: No or almost no uneven gloss and welds were observed.
• B: Slightly uneven gloss was recognized, but almost no welds were observed.
• C: Slight uneven gloss and welds were observed.
• D: Heavy uneven gloss and welds were detected.

Flow lines:

• A: Keine Fließlinien erkannt, oder nur geringfügige Fließlinien wurden an den Endteilen der Spitzen erkannt.
• B: Einige Fließlinien wurden erkannt an Stellen, die 200 mm oder mehr von der Ausgussstelle entfernt waren und deswegen nicht zu bemerken waren.
• C: Auffällige Fließlinien wurden an Stellen erkannt, die weniger als 200 mm von der Ausgussstelle entfernt waren.

A thermoplastic elastomer was injection-molded through an opening formed on the longitudinal side of a mold having a width of 100 mm, a length of 360 mm and a thickness of 2 mm, to make a test piece. The test piece thus obtained was heated at a temperature of 100 ° C for one hour in an oven. Then, the test piece was examined with the naked eye to determine whether or not flow lines (wavy flow patterns) on the surface thereof were caused and examined according to the following criteria, among which classes A and B were practically acceptable.

• A: No flow lines detected, or only slight flow lines were detected at the end portions of the tips.
• B: Some flow lines were recognized at locations 200 mm or more away from the spout point and therefore unnoticeable.
• C: Conspicuous flow lines were detected at locations less than 200 mm from the spout.

Shine of embossed patterns:

The same test piece (2), which for the investigation of irregular shine and welds used was determined in terms of the gloss of the embossed pattern, which were formed thereon, measured at an angle of incidence of 60 ° according to JIS K7105.

Of Further, the obtained olefin-based thermoplastic was Elastomer injection molded by an injection molding machine of inline thread type (Inline Screw Type Injection Molding Machine, "IS130G", manufactured by Thoshiba Kikai Co., Ltd.) at a spraying temperature of 220 ° C, an injection molding of 50 MPa and a casting temperature of 40 ° C, making a test piece to study the elasticity mode and the impact resistance was obtained. The test piece thus obtained was examined by the following procedure to the elasticity mode and to determine the impact strength. The results are in Table 1 shown.

Modulus of elasticity:

One test piece with a strength of 4 mm, a width of 10 mm and a length of 90 mm was in accordance with JIS K 7171 with a variation width of 64 mm and a bending speed measured at 2 mm / min.

Impact resistance:

One Notched test piece with a strength of 4 mm, a width of 10 mm and a length of 80 mm was according to JIS K7110 measured to be at -40 ° C To determine notched impact strength.

Table 1

• ** not according to the invention Table 1 (continued)
  
  Table 1 (continued)
  

• ** not according to the invention Table 1 (continued)
  
  Table 1 (continued)
  

Claims (7)

An olefin-based thermoplastic elastomer comprising a propylene-based resin (A) having a weight average molecular weight (Mw / Mn) to number average molecular weight of 2.5: 1-4: 1: 1, and a copolymer rubber (B) Wherein the amount of the propylene-based resin (A) is 35-60% by weight and the amount of the olefin-based copolymer rubber (B) is 65-40% by weight, and optionally further comprising a styrene-based thermoplastic elastomer (C) in an amount of 1-20 parts by weight, based on 100 parts by weight of the sum of the propylene-based resin (A) and the olefin-based copolymer rubber (B), and a ratio (N1 / SS) of the first one Normalspannungsdiffe has the shear stress (SS) of 0.6: 1-1.4: 1, wherein the first normal stress difference (N1) and the shear stress (SS) are determined by the elastomer at a temperature of 200 ° C and a shear rate of 25.1 sec ^{-1 is} subjected to a step shear test. Thermoplastic elastomer based on olefin according to claim 1, wherein the shearing stress (SS) is not more than 15,000 Pa. Thermoplastic elastomer based on olefin according to claim 1 or 2, wherein the ratio (Mw / Mn) of weight average molecular weight to number average molecular weight of the propylene-based resin (A) is 2.5: 1-3.5: 1. Thermoplastic elastomer on an olefin basis according to one the claims 1 to 3, further comprising a plasticizer for rubbers (D) based on hydrocarbons in an amount of 1-20 Parts by weight, based on 100 parts by weight of the sum of the resin (A) propylene-based and olefin-based copolymer rubber (B), includes. Thermoplastic elastomer on an olefin basis according to at least one of the claims 1 to 4, wherein the elastomer is produced by kinematic heat treatment in the presence of an organic peroxide. Shaped product made of thermoplastic An olefin-based elastomer as in any one of claims 1 to 5 defined, and that is an opening and / or a flat Base plate having a thin-walled area with a Thickness in the range of 5-50 % of the thickness of the flat base plate, a thick-walled area with a thickness in the range of 110-200% of the thickness of the flat Base plate and / or a rib having a thickness in the range of 5-200% of Thickness of the flat base plate includes. Shaped product according to claim 6, wherein the molded Product is a cover for receiving an airbag.